Question

Give an example of diffusion across plasma membrane.

Answer 1

Diffusion:

1. Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration down the concentration gradient.
2. Diffusion can be divided into two main types, namely, simple diffusion and facilitated diffusion.
3. In a cell, water, oxygen and carbon dioxide molecules can pass directly through the cell membrane without requiring any energy along the concentration gradient. This is a form of simple diffusion.
4. Facilitated diffusion can be defined as the passive movement of molecules across the cell membrane from a region of higher concentration to a region of lower concentration by means of a carrier molecule.
5. Example: In amoeba, oxygen (O2) enters the cell by the process of diffusion when the level or concentration of O2 inside the cell decreases.